Ted noise in sound track color sound motion picture film prints with minimal fogged grain rela

ABSTRACT

SOUND TRACK FOGGED GRAIN RELATED NOISE IN PRINTED SILVER SOUND TRACK IMAGES OF DEVELOPED REVERSAL PRINT FILMS IS REDUCED BY INCORPORATION OF A FOGGED GRAIN RELATED NOISE SUPPRESSING AMOUNT OF 2-BENZIMIDAZOLETHIOL INTO THE SILVER SOUND TRACK REDEVELOPER SOLUTION USED FOR REDEVELOPING THE SILVER IMAGE OF THE SOUND TRACK IN A COLOR PICTURE AND SILVER SOUND TRACK DEVELOPING PROCESS.

Sept. 11, 1973 WALSH, JR 3,758,300

COLOR SOUND MOTION PICTURE FILM PRINTS WITH MINIMAL FOGGED GRAIN RELATED NOISE IN SOUND TRACK Filed Dec. 16, 1971 L 06 EXPOSURE /3 l2 RELATIVE United States Patent M COLOR SOUND MOTION PICTURE FILM PRINTS WITH MINIMAL FOGGED GRAIN RELATED NOISE IN SOUND TRACK Edward J. Walsh, Jr., Rochester, N.Y., assignor to Eastman Kodak Company, Rochester, N.Y. Filed Dec. 16, 1971, Ser. No. 208,777 Int. Cl. G03c 5/14, 5/30 US. Cl. 96-4 6 Claims ABSTRACT OF THE DISCLOSURE Sound track fogged grain related noise in printed silver sound track images of developed reversal print films is reduced by incorporation of a fogged grain related noise suppressing amount of 2-benzimidazolethiol into the silver sound track redeveloper solution used for redeveloping the silver image of the sound track in a color picture and silver sound track developing process.

FIELD OF THE INVENTION This invention relates to the production of color sound motion picture film prints utilizing a silver sound track in the film.

DESCRIPTION OF THE PRIOR ART Reversal color print film of the type described in U.S. Pat, 2,533,514, and including a silver image sound track as taught, for example, in US. Pat. 3,243,295 is well known in the photographic art. Processes for developing such color film with such a silver image sound track also are well known, as taught, for example, in US. Pat. 2,193,023, and by Lovick and White, Journal of the SMPTE, vol. 65, pages 591-593. This invention relates to development of the silver sound track in such reversal color print film, conventionally known as Eastman Ektachrome film in one commercial form.

The commercial production of 16 mm. color sound motion picture reversal prints by commercial laboratories often involves a compromise between the best possible print quality and sound and best possible service to customers. In general, three basic print production methods are in use, but each requires some degree of the above compromise. In a first method, reversal prints made directly from reversal originals printed in a dry lab and processed elsewhere offer good quality of print and sound but not best service. In a second method, reversal prints from reversal masters which are processed by a laboratory are usually not equal in quality to that of direct prints. In a third method, use of a color internegative and positive release prints produces good quality and is favored for high numbers of prints; however, the reversal answer prints usually do not match the release prints exactly.

A reversal film, such as that of US. 2,533,514 and of which Eastman Ektachrome Reversal Print Film 7389 and the like, hereinafter referred to as 7389 film, are examples, are available to those skilled in the production in their own laboratories of commercial sound motion picture reversal prints. Film such as 7389 film permits development of both color and sound by the customer in his own laboratory. The 7389 color sound print film incorporates features permiting development by a known process of a silver sound track image on the sound track portion of the print film as currently produced on existing color reversal print films. The processing of such film is carried out generally in accordance with instructions and Patented Sept. 11, 1973 ice processing formulations described in Manual for Processing of Kodak and Eastman Ektachrome Films Using Kodak Process ME-4, Copyright registered 1968 to Eastman Kodak Company. The manual is hereby incorporated herein by reference particularly as to page series 300, 400, 500 and 600.

SUMMARY OF THE INVENTION In processing reversal color print films having a silver sound track image of the above type, it was found that an undesirable amount of fogging often occurs in low exposure areas of the silver sound track upon development and redevelopment of the sound track image. This excessive fogging causes distortion of the sound track configuration and results in poor sound quality during reproduction of the sound. Also, it has been found that the presence of relatively large particles of redeveloped silver in the final sound track cause a sound disturbance referred to as fogged grain related noise when the film is run through a sound motion picture projector.

It has now been found that the fogged grain related noise in the sound track of color sound motion picture prints having a silver sound track such as that of 7389 film, can be suppressed and minimized by including a fogged grain related noise suppressing amount of 2- benzimidazolethiol in the formulation of the redeveloper solution used for redevelopment of the silver in the silver sound track image of the film print in the sound track redevelopment processing step of the Kodak ME-4 process, The amount of Z-benzimidazolethiol advantageously used will range from about 2 to 8 grams per liter of the redeveloper solution hereinafter described.

The problem of fogged grain related noise arises from the normally high fog development occurring upon first, or negative-silver, development of most reversal color films. This unwanted silver development results in unwanted absorption in D minimum areas of the sound track upon completion of normal picture and sound processing. D minimum area absorption results in increased noise during sound reproduction from the film, and thereby lowers the signal-to-noise ratio to unacceptable levels. Commercial processing of film and the like, including, for example, Eastman Ektachrome Reversal Print Film 7390, hereinafter referred to as 7390 film, a color reversal print film, as presently practiced with 7389, involves the introduction of a one-second fix dip after the color developer wash, just prior to bleaching. This fix dip step is a modification of the corresponding Kodak ME4 process, which does not use such a fix dip after the color developer wash. The fix dip modified process is intended to aid in complete silver removal from the image area of the color sound motion picture print As a side etfect, it simultaneously raises the signal-to-noise ratio of the sound track by initiating partial bleaching and fixing of sound track silver. The magnitude of this improvement in one case was measured as a change from 40.6 db (no fix dip) to 44.2 db (with fix dip). Concurrent with this signal-to-noise improvement, however, there was experienced a loss of sound quality due to reduced frequency response. For example, there occurred an increase in frequency response loss from 5.8 db (no fix dip) to 8.1 db (with fix dip). This loss was due to the bleaching and fixing of fine grain silver particles from the sound D maximum areas. These silver grains provide the high resolution image density of the sound image.

Use of a formuatled sound redeveloper made according to the present invention removes first developer fog silver by inhibiting its redevelopment. The silver then is fixed in the normal Kodak ME-4 process fixing solution. By this method, a signal-to-noise increase was noted, from 40.6 db. (standard Kodak ME-4 redeveloper, no fix dip) to 43.1 db (formulation of the invention including 2- benzimidazolethiol). As in the case of the fix dip proc ess, a loss of frequency response was also noted, from -5.8 db (no fix dip) to 6.6 db (Z-benzimidazolethiol used in redeveloper). This result also is due to loss of some fine grain sound image silver in the D maximum area. However, the redeveloper solution of this invention provides a result which is an acceptable compromise with regard to both the signal-to-noise and the frequency response between the processes with and without fix dip. Analogous results were obtained on 7390 film with the pertinent signal-to-noise and frequency response for a given set of sample being as follows:

TABLE 1 Kodak ME-4 Kodak with ME-4 Z-benz- Kodak with imida- Redeveloper solution MID-4 fix dip zolethiol Signal-to-noise, db 40. 2 42. 1 43.1 Frequency response loss, db 6. 9 -11. 3 --8. 7

DESCRIPTION OF THE DRAWING The nature of the fogged grain related noise problem may be better understood by reference to the drawing. The drawing is a chart of the type used to represent the relationship between exposure and the amount of silver formed during development of the silver image. In the chart, charted line A represents the characteristic curve obtained when density (log l/Transmission) is plotted against the relative log of the exposure for the redevelopment of the silver in 7389 film sound track in accordance with the known silver sound track redevelopment processing step according to the Kodak ME-4 process. In the chart, line B represents the curve obtained for redevelopment of the silver in 7389 film sound track in a modified practice of the Kodak ME-4 process wherein part of the fogged silver in the low density area generally indicated by D has been removed by inclusion of a one-second fix dip step.

In the chart, charted line C repreesnts the characteristic curve obtained for the redevelopment step of the sound track using the redeveloper solution of the present invention in the Kodak ME-4 process redevelopment processing step.

The difference in density between the lines A and B indicated by the arrow E in the high density area of the chart relates to the loss in frequency response obtained by use of the fix dip to remove the silver from the low-density area of D. The difference in density between lines A and C shows that the use-of the redeveloper solution of the present invention substantially reduces the amount of fogged grains of silver on the sound track in the D minimum area indicated by D without causing as great a loss of frequency response in the D maximum area, indicated by E, as is caused by the fix dip.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The practice of the invention in development of the sound track in a 16 mm. color print film of the type described above as 7389 is illustrated by the following example.

The following general description provides the background setting for an understanding of the relationship of the invention to the main steps invoved in processing reversal color print film of the type described in US. 2,533,514, including the sound track, in accordance with the referenced Kodak Process ME-4, as herein improved.

The 7389 film is processed in a color print processing machine which is commercially available for such purpose, and which is not part of the present invention. The sound track portion of the color reversal print film is printed onto the reversal print film from a negative sound original. The print film is procesesd through a conventional Kodak ME4 process and the known processing solutions normally used therein with modifications as described hereinafter.

During first development of the reversal films, the sound record in the film is developed to a positive silver image.

Following first development and a subsequent stop step, the film is washed for 30 seconds at :2 F. in a separate deep-tank wash, replenished at about 8 liters per 100 feet of 16 mm. film. The film then travels to a sound hypo station where the undeveloped silver halide is removed from the sound track area by the sound fixer. Before application of the sound fixer, it is important to remove the moisture from the surface of the film for the accurate and uniform application of the sound fixer. An efficient wiper-blade assembly is generally adequate for this purpose. The sound fixer is then applied to the sound track by an applicator. After application, a reaction time of at least 20 seconds must be provided for the complete fixing of the silver halide.

The film next enters a scrub tray portion of the processing machine in which carried-over sound hypo is removed from the film by wiper blades which are flushed first with a low-pressure water spray and then with a hypo eliminator solution. The water and hypo eliminator solution are supplied to the scrub tray at about 330 ml. per 100 feet of 16 mm. film.

After the scrub tray treatment, the film is returned to the main portion of the processing machine to complete washing of the film. The washing is done in a separate 30-second machine deep-wash held at 100i2 F. The solution in this machine is replenished at about 8 liters per 100 feet of 16 mm. film. The deep-tank washes between the sound fixer stations are separate washes and should not be countercurrent washes.

The film next passes through a color developer, a second stop, two wash tanks, bleach and then into a bleach wash. The wash after the bleach is used to remove the bleach from the film, in order to prevent its reaction with the sound redeveloper solution, the silver sound track, and any steel parts used in the sound redeveloper applicator. Normally, the bleach wash should take about 30 seconds in a deep-tank replenished at about 8 liters per 100 feet of 16 mm. film. The bleach converts the silver sound track image developed by the first developer into silver bromide.

After the above bleach removal washing step, the washed film passes through a sound redeveloper station in the processing machine. In the sound redeveloper station, a fogging-type developer (redeveloper solution) serves to reduce the silver bromide of the sound track area of the film to a positive silver image. The reaction time normally will range from a minimum of 15 seconds to a maximum of 30 seconds.

The film is then washed in a scrub tank to remove residual sound redeveloper solution. The water flow is about 250 ml. per 100 feet of 16 film. Rubber Gantrez AN-4651 (1.0% by weight in water) ml 300 Water ml 400 Sodium sulfite g 60 Sodium hydroxide 1 g 60 Hydroquinone g 50 Potassium iodide g.. Ethylene diamine (98% by wt.) ml 15 Hexylene glycol ml 3 Water to make up 1.00 liter.

1 Add as 200 ml. of 10 N NaOH.

While the sound reproduction from the sound track processed as described above is generally suitable for most hearers, it suflfers from the presence of unwanted noise caused by fogged grains as discussed under the summary of the invention, above, both in the form of fine particles and in the form of large grains. The noise factor can be represented as a sound-to-noise ratio. A high value for the ratio indicates a low noise value.

It has now been found that the sound-tomoise ratio in the silver image sound track of the completely processed film is significantly increased by use of an improved sound redeveloper solution as shown in Table 3 for processing of the film. The improved sound redeveloper solution inhibits redevelopment of first developer fogged grains by means of a fogged grain related noise suppressing amount of 2-benzimidazolethiol.

Water to make to 1.0 liter.

A suspending agent consisting of methyl vinyl ethermaleic anhydride copolymers. Gantrez is a registered trademark of General Aniline and Film Corporation.

2 Add as 200 m1. of 10 N NaOH.

The amount of l-benzimidazolethiol advantageously used may range from about 2 to 8 g.; however, 4 g. of 2-benzimidazolethiol per liter of redeveloper solution will usually be sufiicient for obtaining the advantages of the invention and such amount is preferred.

Reversal color sound print film with a silver image sound track processed according to the invention and using the sound redeveloper composition of Table 3 has been found to have substantially less noise defects than similar film processed with the sound developer composition of Table 2. Using as a standard a sound-to-noise ratio of 45 decibels, sound track redeveloped with the sound redeveloper solution of the invention had a soundtonoise ratio of 43.1, compared to a sound-to-noise ratio of 40.6 obtained when the prior art redeveloper solution was used. Using as a standard a frequency response loss of 0.0 decibels (db); sound track redeveloped according to the invention had a frequency response of 6.6 db compared to 5.8 db for the prior art redevelopment, showing very little loss in response.

The function of 2-benzimidazolethiol in the redeveloper solution according to the invention is believed to be as an anti-foggant agent which is particularly effective for the elimination of large grains of Ag" in the redeveloped sound track, substantially as outlined in Table 4.

In accordance with redevelopment step 4, Table 4, of the improved Kodak ME-4 process, the new redeveloper solution of the invention is believed to inhibit conversion of large particles of AgBr so that they cannot be developed to Ag particles which would cause noise in the final sound track image. The fix in step 5, Table 4, then removes these inhibited AgBr particles from the sound track.

The invention has been described in detail with particular reference to the preferred embodiments thereof but it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove and as defined in the claims.

I claim:

1. A redeveloper solution for redeveloping the silver image in a silver sound track of a reversal color print film, said solution comprising a fogged grain related noise suppressing amount of Z-benzimidazolethiol.

2. The redeveloper solution according to claim 1 wherein the 2-benzimidazolethiol is present in an amount of from about 2 to 8 grams per liter of said solution.

3. A process for suppressing fogged grain related noise in the processed silver sound track image of a reversal color print film having such a sound track image said process comprising redeveloping the silver image of the sound track during processing of the film by means of a redeveloper solution comprising a fogged grain related noise suppressing amount of 2-benzimidazolethiol.

4. The process according to claim 3 wherein the 2- benzimidazolethiol is present in an amount of from about 2 to 8 grams per liter of redeveloper solution.

5. A redeveloper solution for redeveloping the silver image in the silver sound track of a reversal color print film and for obtaining a redeveloped sound track having reduced noise output, said solution comprising the following ingredients:

One percent by weight solution in water of a copolymer of methyl vinyl ether Water to make to 1.0 liter.

6. A process for suppressing fogged grain related noise in the processed silver sound track image of a reversal color print film having such a silver sound track image, said process comprising redeveloping the silver image of the silver sound track during processing of the film by means of a redeveloper solution comprising the following ingredients:

One percent by weight solution in water of a copolymer of methyl vinyl ether and maleic anhydride 300 ml. Water 400 ml. Sodium sulfite 60 g. Sodium hydroxide 40 to 80 g. Hydroquinone 40 to 60 g. Potassium iodide 5 to 25 g. Ethylene diamine 0 to 30 g. 2-benzimidazolethiol 2 to 8 g. Hexylene glycol 10 ml.

Water to make to 1.0 liter.

References Cited UNITED STATES PATENTS NORMAN G. TORCHIN, Primary Examiner A. T. SURO PICO, Assistant Examiner U.S. Cl. X.R. 

